BRUSSELS (Reuters) - The Syrian government must ensure its chemical weapons programme is completely and irreversibly dismantled, a NATO official said on Tuesday."The Organization for the Prohibition of Chemical Weapons has already announced that the last declared chemical weapons have been removed from Syria," the official said, asked for comment after a group monitoring the Syrian civil war said government forces carried out a poison gas attack that killed six people. "Having said that, the Assad regime must ensure that its chemical weapons programme is completely and irreversi...